How Important is engine displacement in the grand scheme of thing?

A lot of this depends on the specific engine you're talking about.
Let's say you have a Chevrolet 305, and you want to make power. As it happens, the 305 has a relatively small bore and as a result, it can't fit big valves, which in turn results in limited airflow, effectively choking it at high RPM (where the engine isn't getting the air it needs to make power).
In this specific instance it's very much worth it to go for the bigger, more powerful 350, which has a bigger bore, does have room for big valves and doesn't get choked at higher RPMs, so it's real easy to get even more power out of.

Now let's take and Audi 80/90 with the 2.3 liter 10-valve inline 5. Essentially the lowest level of that engine, not unlike the Chevy 305.
However, since the block is the same as the 20-valve and even 20-valve turbo versions, everything that works for those will work for it, too. When properly built, even what started out as a lowly 2.3 liter making about 133hp, can hit 1000hp.

tl;dr: depends on which engine you're talking about, OP.

>>17691891
Wow an actual good response

>>17691860
What if I told you, that for each atmosphere of boost, you double power, in a perfect world.

Using this concept, you can now understand displacement and why turbo 4cyls can make power.
Obviously, the higher the power an engine makes without boost, the better. So higher displacement is better. No matter what retards driving Hondas say.

>>17691909
>the higher the power an engine makes without boost, the better

But that's wrong you retard

>>17691924
The higher the base power without boost, the more power you will make with boost.
You are retarded.

>>17691934
In an ideal world, yes. In practice, you'll probably blo something up when you boost a high-strung high-compression NA engine.

>>17691934
Not him but you want to start with a relatively low compression engine before boosting it.

>>17691934
See >>17691941

>>17691934
If the engine is built right. If the bigger engine can only take 6-7psi before it blows then your statement is incorrect

>>17691891
in that case it's a ej25(?) from a 2011 subaru impreza 2.5i

>>17691941
Yes, no shit.
The point is, adding displacement, and keeping the HP/L the same will massively grow power under 1bar of boost.

Trading off HP/L for even more displacement, say a bigol Chevy v8 modur making 45HP/L vs a Honda motor making 115HP/L, the V8 modur already makes more HP because of its 6 liters of displacement. And because of its abysmal HP/L, you can screw 1.5Bar in it and make 675HP before loss.

Math is great

>>17691860
As engines get more complicated and computer-controlled, it becomes more difficult to improve them yourself. Not impossible, but it's hard to find (for example) heavily modified FR-S/BRZs that are reliable in heavy track running. I've seen too many of them overheat and fall into limp mode after just a few laps.

But the real reason to get the sport model instead of upgrading your engine is that there are so many parts involved in making a car sporty: stiffer bushings in the suspension, motor mounts, springs, dampers, steering tuning, transmission tweaks... those are often worth the cost of just upgrading the whole car.

>>17691958
There are turbo variants of the EJ25, so with the right parts you can in theory make more power than the 2 liter. The advantage of the 2.0 turbo is that it's already boosted so making more power is relatively easy, but a fully built 2.0 should lose out to a fully built 2.5 running the same boost, compression, fuel mixture and so on.

>>17691968
Yeah, more displacement means more potential airflow and more potential power. It's just that "more power before boost = more power after boost" is inaccurate because one of the most common ways of increasing NA power is to increase compression, which means you can't run as much boost through them as you potentially could with a lower power, lower compression variant.

>>17691968
>I completed high school algebra

Fuck off retard

>>17691968
>Math is great
But your grammar is not.

>>17691998
Well yes, compression ratio and boost generally don't mix.
But another way to add N/A power is to full retard the displacement.

>>17691860
It doesn't matter.

The more power you make, the more fuel you need.

More power and fuel economy don't go hand in hand.